The present invention relates to an analog type stop watch which can measure the time from the starting to the stopping of a start/stop switch, display measurement data by means of hands, and further, display a plurality of split times as elapsed times.
Generally, in sports competitions wherein a plurality of players compete for speed, such as track-and-field and swimming, the finishing times of the respective players must be recorded in the order of their arrival. When a single person measures the elapsed times of the plurality of players, he necessarily uses a single stop watch to measure their respective finishing times. As examples of stop watches of this type, digital type stop watches are known. More specifically, a digital type stop watch of this type has a counter for measuring the elapsed time since the start, a start/stop switch, and another switch for recording the elapsed time since the start (generally called "elapsed time" or "split time"; to be referred to as "split time" in the present specification). Every time the split time recording switch is depressed, the content of the counter at that time is stored in an electronic circuit. To display the split time, data stored in the electronic circuit is displayed on a digital display means after measurement.
In other words, with digital type stop watches, if an electronic circuit for storing data during measurement is provided, arbitrary measurement data can be selectively displayed instantaneously. As described above, a split time stored in the electronic circuit is not displayed after measurement. Therefore, it is easy for a digital type stop watch to display a split time for a predetermined period of time when the switch is depressed, allowing the operator to write the displayed time on a sheet of paper or the like. Thereafter, the stop watch is instantaneously switched to display the present time being measured since the start, and is prepared for the next measurement.
In contrast to this, since conventional analog stop watches perform display mechanically, or geometrically, they cannot be instantaneously switched, in order to display different measurement data. Accordingly, they can merely measure the time from start to finish, and do not allow confirmation of a plurality of split times during or after measurement. When the operator wishes to know a split time, he must read the momentary positions of moving hands, resulting in erroneous reading.
U.S. Pat. No. 4,211,066 entitled "STOP WATCH" by Kusumoto describes a stop watch wherein the above drawbacks are eliminated and the hands of a stop watch are stopped to display a split time. More particularly, according to the technique of this U.S. Patent, when a switch of a stop watch is depressed to obtain a split time during measurement, the hands are stopped, and the timer unit is operated to measure the time period during which the hands are stopped. When the switch is reactivated, the hands are moved or shifted quickly to compensate for the time during which they have been stopped.
With the technique of this Patent, however, each elapse time can be displayed only once and the next elapse time can be obtained only after the hands are moved by the quick-shift operation. As a result, the stop watch operation becomes considerably complex. In addition, when differences among the respective split times of a plurality of persons are small, such split times cannot be measured.
The unit of measurement of a stop watch is 1/100 or 1/10 second, and thus is very short. If a pulse shorter than such a unit of measurement is applied to move the hands of a stop watch to catch up with the present time measured from the start, it may damage the mechanism of the watch by the force of its drive torque. In addition, when a split time is displayed for a long period of time and is then canceled, it takes considerable time for the hands to catch up with the present time being measured, and the next split time cannot be measured. Furthermore, once measurement of all the split times is finished, each of them cannot be displayed again. Therefore, each split time must be written down in record paper during measurement, resulting in inconvenience.